Noise Control In Highway Construction

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Noise ControlIn Highway Construction

• Kwangseog Ahn, MS and Susan Moir, MS

Department of Work Environment University of
Massachusetts Lowell www.uml.edu/Dept/WE/COHP
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Big Dig

• Highway construction in Boston
• Replacing old elevated highway
• Constructing tunnels

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Study Objectives

• Evaluate noise
• Reduce exposures
• Recommend practical controls

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Noise In Highway Construction

• Widespread multiple sources
• Exposed at/close to sources
• Short-term peak exposures
• Vibration chemical hazards
• Safety hazards

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Noise ExposureEvaluation Methods

• Personal samples
• Octave band samples
• Walkthrough observation
• Area samples
• Conversations with safety officers and workers

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Targeted Sources

• Drilling rig
• Portable air compressor
• Power tool for tying rebars
• Impact/impulsive noise

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Drilling Rig
exhaust
engine
exhaust
engine
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Air Compressor
exhaust
engine
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Power Tool Tying Rebars
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Short-term Noise Levels
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Octave Band Spectra
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Noise Control

• Ideal control hierarchy
• 1. Engineering
• 2. Administrative
• 3. Hearing protectors

• Practical control hierarchy
• 1. Hearing protectors
• 2. Administrative
• 3. Engineering

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Hearing Protectors

• Widely used
• Workers often not wearing
• Not sufficient protection
• Supplemental to engineering and administrative
  controls

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Noise Reduction Rating (NRR)

• Single-number rating
• Tested in laboratory
• Derated under real conditions (NIOSH criteria,
  1998)
• Earmuffs subtract 25
• Formable earplugs subtract 50
• Other earplugs subtract 75

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Required NRR (dB)
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Assessment of Noise Levels Existing methods

• Noise dosimetry
• Task-based dBA levels
• Published reference values
• Takes too much time
• Sources/technology not available

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Administrative Controls

• Reduce exposure time
• Adjust worker schedule
• Noise perimeter zone
• Keep unnecessary workers out of high noise zone
• Only designated workers within zone

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Calculatinga Noise Perimeter Zone

• 1. Measure sound pressure level at a distance
  from a noise source
• 2. Measure distance between the noise source and
  measurement point
• 3. Convert sound pressure to estimated sound
  power (Table 1)
• 4. Calculate a Noise Perimeter Zone (Table 2)
• 5. Estimate maximum exposure time within a Noise
  Perimeter Zone (Table 3)

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Calculatinga Noise Perimeter Zone

• 1. Measure sound pressure level at a distance
  from a noise source
• 2. Measure distance between the noise source and
  measurement point
• 3. Convert sound pressure to estimated sound
  power (Table 1)
• 4. Calculate a Noise Perimeter Zone (Table 2)
• 5. Estimate maximum exposure time within a Noise
  Perimeter Zone (Table 3)

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Table 1. Converting Sound Pressure Measurement
to Sound Power Level (dB)
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Sound Power Level
Sound Pressure Level
Sound Power Level
2X
X
110 dB
80 dB
74 dB
Single Number Index
Depending on Distance
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Calculatinga Noise Perimeter Zone

• 1. Measure sound pressure level at a distance
  from a noise source
• 2. Measure distance between the noise source and
  measurement point
• 3. Convert sound pressure to estimated sound
  power (Table 1)
• 4. Calculate a Noise Perimeter Zone (Table 2)
• 5. Estimate maximum exposure time within a Noise
  Perimeter Zone (Table 3)

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Table 2. Calculating Noise Perimeter Zone from
Sound Power Measurement
 
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Calculatinga Noise Perimeter Zone

• 1. Measure sound pressure level at a distance
  from a noise source
• 2. Measure distance between the noise source and
  measurement point
• 3. Convert sound pressure to estimated sound
  power (Table 1)
• 4. Calculate a Noise Perimeter Zone (Table 2)
• 5. Estimate maximum exposure time within a Noise
  Perimeter Zone (Table 3)

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Table 3. Maximum Exposure Time Within a Noise
Perimeter Zone
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Engineering Controls

• Internal combustion engines - acoustical
  enclosures and barriers
• Exhausts - mufflers/silencers
• Vibrating parts, pipes, etc. - isolation/sound
  absorbing material
• Good maintenance

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Noise Controlin Highway Construction

• Engineering and administrative hearing
  protectors
• Full support of top management
• Purchasing policy
• Construction plan
• Hearing conservation program

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References -Noise Exposures In Construction
Workers

• Blute N et al, Appl Occup Environ Hyg
  14(9)632-641 (1998)
• Legris M and Poulin P, AIHAJ 59774-778 (1998)
• Neitzel R et al, AIHAJ 60807-817 (1998)
• Sinclair JDN and Haflidson WO, Appl Occup Environ
  Hyg 10(5)457-460 (1995)